Synthesis of chemicals derived from biomass using heterogeneous catalysts with water as a solvent elegantly fits into the realm of sustainable chemistry. In this work, a novel heterogeneous palladium copper bimetallic catalyst supported on zirconia is synthesized and fully characterized. This catalyst is used in one pot synthesis of γ-valerolactone, 1,4-pentanediol and 2-methyl tetrahydrofuran from levulinic acid and hydrogen using water as solvent. The catalyst consists of 1% palladium and 29% copper supported on zirconia and is characterized per se and after reuse by using elemental analysis, FTIR, NH3-TPD, XRD and BET surface area, XPS, SEM and TEM analysis. This is first ever report on direct synthesis of 1,4-pentanediol and 2-methyl tetrahydrofuran using water as solvent. Reaction mechanism and kinetic modeling was done to validate the experimental results. The results reported are thus a combination of synthesis of a novel catalyst with its full characterization, its application in a novel synthesis route, description of the synthesis mechanism and kinetic modelling and proof of the robustness of the developed catalyst by reusing it for four catalytic cycles.Developing strategies for synthesis of second generation biofuels is a current trend. The technologies developed ought to be inexpensive and sustainable in order that both the developing countries and developed countries could adopt them. Valorization of levulinic acid (LA) derived from renewable source; for instance, glucose and fructose, is a viable option because the products derived from it are in tune with the current liquid fuel infrastructure. 1 BioMetics Inc. developed the biorefine process to produce LA at 50-70% yields from cellulosic feedstockand estimated a large scale plant (1000-2000 ton/day) could produce LA for $ 0.09-0.11 per kg. 2 There are abundant technologies for valorization of LA to γ-valerolactone(GVL) (Table 1). 3-12 Most of these technologies employ external hydrogen as a source for hydrogenation with a suitable catalyst. Ruthenium complexes bearing monodendate phosphorous ligands are the mainly used homogeneous catalysts whereas Ru, Pd, Pt, Ni, Rh, Ir, Au supported on neutral support like silica or metal oxides have been used as heterogeneous catalysts. 13 There are very few reports on synthesis of GVL from LA using heterogeneous non noble catalysts.Cu/ZrO 2 and Cu/Al 2 O 3 made by co-precipitation have been reported for hydrogenation of LA and methyl levulinate to GVL. 9 Methanol and water were used as solvent. Cu/ZrO 2 catalyst gave 100% selectivity towards GVL. However, a copper carboxylate complex was formed which resulted in leaching of the copper catalyst when water was used as a solvent. Another route to achieve formation of GVL from LA is by transfer hydrogenation. Formic acid and LA mixture in 1:1 proportion has been used with Cu/ZrO 2 catalyst prepared by oxalate gel precipitation for selective synthesis of GVL. 14 Direct synthesis of 1,4-pentanediol (PDO) with 70% yield was achieved using Mo modified Rh/SiO 2 catal...

Energy and the environment are intimately related and hotly debated issues. Today’s crude oil-based economy for the manufacture of fuels, chemicals and materials will not have a sustainable future. The over-use of oil products has done a great damage to the environment. Faced with the twin challenges of sustaining socioeconomic development and shrinking the environmental footprint of chemicals and fuel manufacturing, a major emphasis is on either converting biomass into low-value, high-volume biofuels or refining it into a wide spectrum of products. Using carbon for fuel is a flawed approach and unlikely to achieve any nation’s socioeconomic or environmental targets. Biomass is chemically and geographically incompatible with the existing refining and pipeline infrastructure, and biorefining and biofuels production in their current forms will not achieve economies of scale in most nations. Synergistic use of crude oil, biomass, and shale gas to produce fuels, value-added chemicals, and commodity chemicals, respectively, can continue for some time. However, carbon should not be used as a source of fuel or energy but be valorized to other products. In controlling CO2 emissions, hydrogen will play a critical role. Hydrogen is best suited for converting waste biomass and carbon dioxide emanated from different sources, whether it be fossil fuel-derived carbon or biomass-derived carbon, into fuels and chemicals as well as it will also lead, on its own as energy source, to the carbon negative scenario in conjunction with other renewable non-carbon sources. This new paradigm for production of fuels and chemicals not only offers the greatest monetization potential for biomass and shale gas, but it could also scale down output and improve the atom and energy economies of oil refineries. We have also highlighted the technology gaps with the intention to drive R&D in these directions. We believe  this article will generate a considerable debate in energy sector and lead to better energy and material policy across the world. Graphic abstract

Nanofibrillated cellulose was synthesized by magnetically separable 4-oxo-2,2,6,6 tetramethylpiperidine-1 oxyl (TEMPO) mediated oxidation and mechanical disintegration of wood pulp.

Bark serves multiple functions for a tree by combining protection and fluid transport. The tissue itself is composed of multiple types of material that includes typical cell wall structural polymers of cellulose and lignin, as well as extractives. With suitable fractionation, these bark constituents may serve to help valorize biomass when converted into feedstocks for polymeric precursors, such as aromatic polyols. In this study, organosolv processing was used to solubilize around 50% of pine bark (PB) and oak bark (OB), followed by the recovery of around 20% crude lignin. Two-dimensional 1 H− 13 C heteronuclear single quantum coherence (2D HSQC) NMR and 13 C NMR revealed the crude lignin also contained mixed polyphenolics, suberin-compounds, and carbohydrate compounds, especially for PB. To optimize the extraction process, a two-level factorial design was used to study the impacts of temperature, ethanol concentration, and solid loading on the yield and related characteristics of crude lignin. Increased temperature and ethanol concentration during processing allowed more solubilization of the components along with the extraction of crude lignin with higher yield. The correlation analysis found that the thermal stability of crude lignin had a direct relationship with aromatic hydroxyl group content, while the glass transition temperature was impacted by the lower molar mass components contained in the crude lignin. Overall, the study showed promise to solubilize a high portion of bark material and provided insight into structure−property relationships of crude lignin-derived from an important, yet underutilized resource as a function of processing conditions.

Three kraft lignins were subjected to oxidative depolymerization using a magnetically separable and reusable nitroxyl radical catalyst under greener conditions without the use of additional alkali.

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